Vapor generating unit



Dec. 24, 1963 H. a. STALLKAMP VAPOR cznsmmc uurr 3 Sheets-Sheet 1 FiledMarch 5, 1961 FIGJ mmvron Huber? G. Stallkamp ATTORNEY Dec. 24, 1963 H.G. STALLKAMP VAPOR GENERATING UNIT 3 Sheets-Sheet 2 Filed March 3, 1961FIG? IHI I'l INVENTOR? Hubert G. Sia'l'l jkamp ATTORNEY Dec. 24, 1963 H.a. STALLKAMP VAPOR GENERATING UNIT med March a, 1961 s Sheets-Sheet :s

mmvron. Hubert G. Srallkamp 6 AT TORNEY United States Patent 3,115,122VAIPQR GENERA'HNG UNIT Hubert G. Stallkamp, Akron, Ohio, assigner to TheBabcock & Wilcox Company, New York, N.Y., a corporation of New JerseyFiled Mar. 3, 1961, @r. No. 93,173 3 Claims. (Cl. 122-235) The presentinvention relates to the construction of fluid heating units and moreparticularly relates to an improvement in the fluid flow system of avapor generator of the type disclosed in US. Patent 2,840,049.

When vapor generating units are operated under combustion conditionswhere the gases of combustion are maintained at high pressures, it is ofconsiderable structural advantage to construct the unit with a circularcrosssection. A circular section combustion chamber and convection gaspass of such a vapor generator can readily withstand high furnacepressure operation due to the inherent structural strength of aconstruction involving such circular sections.

In the present invention, a vapor generating unit is provided whereinthe furnace and the convection gas passes of the unit are enclosed in acylindrical setting. The confining walls of the unit are lined withvapor generating tubes for the absorption of heat and the protection ofwalls. Advantageously, the downcomer tubes of the vapor generator flowcircuit are bent out of alignment with the walls of the furnace so as toform a bustle or annular chamber surrounding the furnace walls. Thebustle or annular chamber advantageously provides a housing for theintroduction of gaseous fuels and air.

More specifically, in the present invention the riser or steamgenerating tubes lining the furnace and convection gas pass portions ofthe unit are positively provided with make-up fluid to insure adequatethermosiphonic circulation in the unit over the entire load range. Thisis accomplished in the present invention by the provision of separatedownflow fluid flow paths feeding separate portions of the furnace andthe convection gas pass. The construction is particularly economical toconstruct and assemble and efliciently insures adequate naturalcirculation of fluid through the unit.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which I have illustrated and described a preferred embodimentof the invention.

Of the drawings:

FIG. 1 is a sectional elevation of a vapor generating unit constructedin accordance with the present invention;

FIGS. 2, 3 and 4 are sectional views taken on the lines 22, 33 and 4-4respectively of FIG. 1; and

FIG. 5 is an enlarged partial section taken on the lines 5-5 of FIG. 1.

The vapor generating or fluid heating unit illustrated in FIG. 1 isarranged for a gaseous fluid flow over and along the heating surfaces ofthe unit substantially as shown in US. Patent 2,840,049. As disclosed insaid patent, and shown in FIG. 1, means are provided in the lowerportion of the cylindrical setting for the combustion of a fuel.Specifically, the lower portion or furnace 11 includes vertically spacedrows of burner ports 12 for the introduction of a high heat Value fuelthrough burners 13 with a row of low heat value fuel inlet ports 14positioned intermediate the level of the two high heat value fuel burnerports 12. A second row of low heat value fuel inlet ports 15 is spacedbelow the lower level of the high heat value fuel burner ports 12. Asshown in FIGS. 4 and 5, the high heat value fuel burners 13 are arrangedwith their longitudinal axes substantially radial with respect to thefurnace 11, while the low heat value fuel inlet ports 14 and 15 arearranged to discharge fuel into the furnace with tangential componentsof movement. As shown, the burners 13 are constructed for the use offuel oil, although other high heat value fuels, such as natural gas orthe like, may be used with suitable changes in the burners. The low heatvalue fuel inlet ports may be used for the introduction of CO containinggases obtained from the regeneration of the catalyst used in ahydrocarbon reforming process.

The upper end portion of the furnace 11 is provided with an orificebaffie 16 which aids in mixing the products of combustion resulting fromthe burning of both the low and high heat value fuels. An annular airchamber 17 extends from an upper position adjacent the orifice baflle16, on the exterior side of the furnace 11 to the bottom of the furnace.Above the orifice baffle, the gases of combustion are deflected towardone side of the unit by a wing or nose baflle 261 which extendstransversely across the unit at a position upwardly adjacent the levelof the orifice baffle 16.

The portion of the setting between the orifice b-aflle and the wingbaflle constitutes a radiant heat exchange chamber or Zone 21 whereinthe gases of combustion are partially cooled and in passing upwardlythrough the gas flow passageway 22 between the nose baffle 20 and theopposite wall are directed into a convection gas pass 23. The convectiongas pass is provided with rows of generally upright tubes 24 extendingbetween and opening into horizontally disposed upper and lower drums 25and 26, respectively. The upper drum is located adjacent the roof 27 ofthe setting, while the lower drum 26 is positioned immediately above andis protected by the nose baflle 20. The gas outlet 30 from the settingis adjacent the upper drum 25 andin general vertical alignment with thewing baffle 20 so that the gases of combustion flow in a generallyhorizontal direction across the bank of convection heating tubes 24 tosubsequently discharge upwardly through the outlet 30. Naturalcirculation occurs through the tubes 24 between drums 25 and 26, withthe cooler tubes adjacent the gas outlet 30 serving as downcomers tosupply fluid to the lower drum 26.

Thus, with the construction described, the flow of the heating gasesthrough the unit is substantially the same as that disclosed in said US.patent. The construction is such as to provide a simple and effectiveheat trap for the products of combustion generated in the furnace 11 inthe lower portion of the setting, and the generation of steam.

In accordance with the present invention, a lower header 31 supplieswater to the lower or inlet end of the circumferential row of tubes 3-2defining the circular wall of the furnace 11, the radiant heatingportion 21 and the convection heating portion 22 of the unit. The header31 is circular and is divided into two separate sections 31A and 31B bymeans of diaphragms 33 positioned in the header. The tubes 32 in thewall of the furnace 11 extend upwardly to the level of the orificebaflle 16 whereat alternate tubes 32A are bent inwardly toward thecenter of axial centerline of the cylindrical setting 10 and wethereafter bent towards the circumferential row of wall tubes to returnto the wall configuration. This construction is illustrated in FIGS. 1and 3 of the drawings wherein the wall tubes are indicated beneath theprotective covering of refractory materials 33. Alternate tubes 3213 inthe furnace row extend in a vertical direction for wall support and tomaintain the cylindrical configuration of the structure.

The circumferential row of wall tubes 32 representing approximately /3of the tubes in the setting are extended upwardly through the radiantheating zone 21 and the passageway 22 of the unit to open into anarcuate collecting header 34 positioned downwardly adjacent the upperdrum 25. The steam and water mixture delivered by the wall tubes 32 tothe upper header is discharged into the drum through roof tubes 35. Aportion of the wall tubes 32 identified as 32C in FIGS. 1 and 2extending upwardly from the lower header 31 toward the lower drum 26open into the lower drum with an aligned group of tubes thereafterpassed upwardly in the sa ine wall row alignment from the lower drum toopen directly into the upper drum 25. All of the above described tubesopen at their lower end to the header section 31A.

The remaining wall tubes 32. extended upwardly from the lower headersection 31B and forming the upwardly aligned portion of the orificebafile 16 are all bent inwardly of the furnace to form the nose bathe20. Above the orifice baffle 16, these tubes are designated as 36 andthe tube arrangement is shown particularly in FIGS. 1 and 2. The tubes36 extend upwardly through zone 21, bend forwardly and upwardly alongthe hot face of the nose baffle 29, extend upwardly across the nose 37of the bafile and then bend in a rcanwa-rd direction to open into thelower drum 26. Thus, the riser tubes of the unit described completelyenclose the furnace 11 including the orifice bailie 16, and theradiation zone 21 including the surface of the wing bafile 20. Inaddition, the riser tubes enclose a major segment of the gas passageway22 including wall tubes connecting the drums 25 and 26. As hereinafterdescribed, the remaining rear segment of the wall of the convection zone23, above the nose battle 20, which is the coolest wall portion of theunit, is lined by downcomer tubes 4% to complete the tube rowsassociated with the walls of the cylindrical setting 19.

The downcomer tubes 4t) forming the rear portion of the wall above thewing baffle receives water from the water space of the upper steam andwater drum through connectors 39 and an arcuate header 41. The header ishorizontally disposed substantially at the elevation of the header 34and forms a segment of a circle of substantially the same radius as theheader 34 and the cylindrical wall of the setting It). The uprightdowncomer tubes 40 extend downwardly parallel to and behind the risertubes 36 in the zone 21. This construction is shown in FIG. 3, where thetubes 40 are embedded in plastic refractory material 42 and areprotected by the tubes 36 from direct radiation of the hot gases passingthrough the zone 21. The tubes 40 are bent out of wall alignment towardthe exterior of the unit at an elevation adjacent the upper edge of theorifice baffle 16 to define the outer wall 43 of the annular chamber 17surrounding the furnace, and open into the lower header 318.

As shown particularly in FIG. 1, the make-up water delivered to theforward portion 31A of the lower header 31 originates in the lower drum26. This water flows downwardly through exterior downcomers 44 to aheader 45 positioned upwardly adjacent but on the exterior side of theorifice baffle 16. The header 4'5 for-ms the segment of a circle havinga radius greater than that of the wall defined by the tubes 32. Thedowncomer tubes 46 leading downwardly from the header 45 are bentoutwardly of the cylindrical casing to define approximately /3 of theouter circumferential wall 43 of the annular chamber 17 enclosing thefurnace portion of the unit. The lower ends of the tubes 46 open intothe portion 3 1A of the lower header 31.

In the illustrated embodiment of the invention, the furnace 11 isarranged for the combustion of a low heat content gas having arelatively high sensible heat and a minor proportion of combustible COgases therein. The low heat value fuel can be burned only in a furnacemaintained at a temperature in excess of approximately 4 1500 F. Thistemperature is attained by the combustion of a high heat value fuel,such as fuel oil, introduced through the fuel burners 13.

The construction and arrangement of the high heat value fuel burners isillustrated in FIG. 4 wherein the tubes 32 in the wall of the furnace 11are covered by refractory material 47 and the tubes are displaced out ofthe plane of the wall in the vicinity of the burner ports 12. When fueloil is burned as a supplemental high heat content fuel, the oil burner13 is inserted in the burner ports 12 for the introduction of the highheat value fuel. The air necessary for proper combustion of the highheat value fuel is introduced through the usual louvre equippedregisters 43, supplied through upright chambers 50 formed by verticallydisposed dividing partitions 51 extending from the lower end of theannular chamber 11 to a location above the upper row of burners 13. Thepartitions are spaced on opposite sides of each of the burner ports 12to provide the separate flow paths for combustion air leading to each ofthe vertical rows of high heat content fuel burners 13. Between thepartitions which define the upright chambers 59 are passageways 52 forthe introduction of the CO contain ing gases to and through the low heatcontent burner ports 1'4 shown in phantom on FIG. 4 and in enlargeddetail in FIG. 5.

He combination air enters the channels or chambers 50 from a plenumchamber 60 located below the floor 61 of the furnace -11 being suppliedwith superatmospheric pressure air from a forced draft fun (not shown)through a connecting duct 62. Only the chambers 50 open to the plenumchamber 69, and each chamber 50 is closed at the top by a horizontallydisposed plate 63, spaced above the uppermost row of burners 13 andwhich extends between the partitions '51 only above each chamber 53.

The ports 14 and 15 open to the passageways 52 which are supplied withlow heat value gas from a duct 64 which enters the annular chamber 17above the plates 63. With this construction, the annular chamber 17forms an annular plenum above the plates 63 for distributed How to eachof the passageways 52 and thence through the ports 14 and 15.

In the embodiment illustrated in FIGS. 1 and 4, the high heat value fuelis discharged by the burners 13 into the furnace 11 in a radialdirection. As shown in phantom in FIG. 4 and in FIGS. 1 and 5, the lowheat value fuel inlet ports 14 and 15 are constructed to introduce thegases into the furnace at an angle of approximately 45 as indicated inFIG. 4 and with a tangential component of motion. The projected axialcenterlines 56 of such low heat value fuel inlet ports intersect animaginary circle 57 spaced inwardly of but closely adjacent to therefractory lining of the furnace walls. With this construction, the lowheat content fuel sets up a violent swirling motion for intimate mixingof the gases of combustion resulting from the conversion of the CO gasesto CO as encouraged by the temperature level maintained in the furnace.The high heat value fuel introduced by the burners will form a centralcore of high temperature flames from the combustion thereof. The centralcore will rapidly mix with and encourage the combustion of the low heatvalue fuel. The orifice baffle 16 will further insure complete andintimate mixing between the products of combustion of the two fuelspassing upwardly through the unit.

In the operation of the unit of the type described, the waste gasescontaining CO may contain sufficient oxygen therein for the conversionof the CO to CO under the temperature conditions prevailing within thefurnace. Under these conditions, the combustion air admitted through thehigh heat value inlet ports 12 will be generally suflicient to insurethe combustion of such fuel, for example, of the theoretic airrequirements for this fuel. Sometimes, the CO containing gases will notcontain suflicient oxygen for the conversion of the CO -to CO Underthese conditions, it will be necessary to add sufli'cient excess airthrough the high heat value inlet ports to provide the oxygen necessaryfor the combustion of the CO gases. Thus, the air delivered to the highheat value burners will be regulated in accordance with the requirementsof the particular installation.

The unit described has a furnace diameter of 17 feet, and is supplied by6 high heat value burners and 12 low heat value burner ports. Such aunit is capable of burning 355,000 c.f.m. of CO bearing gases having anincoming gas temperature of 1050 F. With a CO content of approximately7.5% by volume, and burning sufficient high heat value fuel to maintaina furnace temperature of approximately 1800 F., the unit will generate200,000 pounds of steam per hour at 625 psi. (pounds per square inchgage). Larger or smaller units may be constructed with a greater orlesser number of burners, and a correspondingly changed steam generatedcapacity. Within the ability of the furnace described to burn COcontaining gas, the natural circulation fluid flow system of theinvention will be entirely adequate.

While in accordance with the provisions of the statutes I haveillustrated and described herein the best form and mode of operation ofthe invention now known to me, those skilled in the art will understandthat changes may be made in the form of the apparatus disclosed withoutdeparting from the spirit of the invention covered by my claims, andthat certain features of my invention may sometimes be used to advantagewithout a corresponding use of other features.

What is claimed is:

l. A fluid heater having an upwardly elongated setting of circularhorizontal cross-section defined by walls having a circumferential rowof substantially upright tubes therein, spaced upper and lowerhorizontally disposed drums connected by substantially upright banks oftubes extending transversely across and positioned in the upper portionof said heater setting, means defining a gas outlet from said settingbehind said upper drum and between the drum and the adjacent wall, meansin the lower portion of said heater setting for generating hotcombustion gases, wing baflie means extending from said wall andpositioned beneath said lower drum in general vertical alignment withsaid gas outlet, the segmental portion of the circumferential row ofupright wall tubes directly beneath said wing portion forming risertubes and being bent inwardly out of wall alignment along said wingbaflle to open into said lower drum, the segmental portion of thecircumferential row of upright wall tubes directly above said wingportion opening to said upper drum and forming downcomers and beingoff-set outwardly of the wall and supplying fluid to the lower end ofsaid riser tubes, and means including external downcomers for fluid flowfrom said lower drum to the lower end of the remaining segmental portionof the circumferential row of tubes in said wall, said last named tubesforming riser tubes extending upwardly along the corresponding segmentalportion of the walls of said setting to discharge into said upper drum.

2. A fluid heater having an upwardly elongated setting of circularhorizontal cross-section defined by walls having a circumferential rowof substantially upright tubes therein, spaced upper and lowerhorizontally disposed drums connected by substantially upright banks oftubes extending transversely across and positioned in the upper portionof said heater setting, arcuate upper headers connected with tubes inthe walls of said heater and with said upper drum, means defining a gasoutlet from said setting between said upper drum and an adjacent wall ofsaid setting, means in the lower portion of said heater setting forgenerating hot combustion gases, wing baffle means extending from saidwall and positioned beneath said lower drum in general verticalalignment with said gas outlet, the inner end of said wing bafllecooperating with a segmental portion of said wall to define a restrictedgas flow path therebetween, a segmented annular lower header connectedwith the lower ends of the tubes in said circumferential row of tubes,the segmental portion of the circumferential row of upright wall tubesdirectly beneath said wing portion forming riser tubes and being bentinwardly of said setting out of wall alignment along said wing baflie toopen into said lower drum, the segmental portion of the circumferentialrow of upright 'Wall tubes directly above said wing portion opening toone of said upper arcuate headers and forming downcomers and beingoff-set outwardly of the wall and supplying fluid to a segmental portionof said lower annular header, and means including external downcomersfor fluid flow from said lower drum to another segmental portion of saidannular header to supply fluid to the remaining segmental portion of thecircumferential row of tubes in said Wall, said last named tubes formingriser tubes extending upwardly along the walls of said setting with amajor portion of said tubes discharging into the other of said arcuateupper headers and the remainder discharging directly into said drums.

3. A fluid heater having an upwardly elongated setting of circularhorizontal cross-section defined by walls having a circumferential rowof substantially upright tubes therein, spaced upper and lowerhorizontally disposed drums connected by substantially upright banks oftubes extending transversely across and positioned in the upper portionof said heater setting, means defining a gas outlet from said settingbetween said upper drum and an adjacent wall of the setting, means inthe lower portion of said heater setting for generating hot combustiongases, wing baffle means extending from said wall and positioned beneathsaid lower drum in general vertical alignment with said gas outlet, thesegmental portion of the circumferential row of upright wall tubesdirectly beneath said wing portion forming riser tubes and being bentinwardly out of wall alignment along said wing baffle to open into saidlower drum, the segmental portion of the circumferential row of uprightwall tubes directly above said wing portion opening to said upper drumand forming downcomers and being oflY-set outwardly of said settingwalls at an elevation spaced below said wing baflle and extendingdownwardly to supply fluid to a separate header opening to lower ends ofsaid riser tubes, and means including external downcomers and an uprightrow of circumferentially spaced downcomer tubes off-set outwardly of thewalls of said setting connected with a separate header opening to thelower ends of the remaining segmental portion of the tubes in said wall,said last named tubes forming riser tubes extending upwardly along thewalls of said setting, said ofi-set downcomer tubes being radiallyspaced from said setting walls to form an annular chamber surroundingthe lower portion of said fluid heater.

References Cited in the file of this patent UNITED STATES PATENTS1,892,661 Hulsart Dec. 27, 1932 1,935,272 Kuhner Nov. 4, 1933 4,943,539Kerr Jan. 16, 1934 2,840,049 Durham June 24, 1958

1. A FLUID HEATER HAVING AN UPWARDLY ELONGATED SETTING OF CIRCULARHORIZONTAL CROSS-SECTION DEFINED BY WALLS HAVING A CIRCUMFERENTIAL ROWOF SUBSTANTIALLY UPRIGHT TUBES THEREIN, SPACED UPPER AND LOWERHORIZONTALLY DISPOSED DRUMS CONNECTED BY SUBSTANTIALLY UPRIGHT BANKS OFTUBES EXTENDING TRANSVERSELY ACROSS AND POSITIONED IN THE UPPER PORTIONOF SAID HEATER SETTING, MEANS DEFINING A GAS OUTLET FROM SAID SETTINGBEHIND SAID UPPER DRUM AND BETWEEN THE DRUM AND THE ADJACENT WALL, MEANSIN THE LOWER PORTION OF SAID HEATER SETTING FOR GENERATING HOTCOMBUSTION GASES, WING BAFFLE MEANS EXTENDING FROM SAID WALL ANDPOSITIONED BENEATH SAID LOWER DRUM IN GENERAL VERTICAL ALIGNMENT WITHSAID GAS OUTLET, THE SEGMENTAL PORTION OF THE CIRCUMFERENTIAL ROW OFUPRIGHT WALL TUBES DIRECTLY BENEATH SAID WING PORTION FORMING RISERTUBES AND BEING BENT INWARDLY OUT OF WALL ALIGNMENT ALONG SAID WINGBAFFLE TO OPEN INTO SAID LOWER DRUM, THE SEGMENTAL PORTION OF THECIRCUMFERENTIAL ROW OF UPRIGHT WALL TUBES DIRECTLY ABOVE SAID WINGPORTION OPENING TO SAID UPPER DRUM AND FORMING DOWNCOMERS AND BEINGOFF-SET OUTWARDLY OF THE WALL AND SUPPLYING FLUID TO THE LOWER END OFSAID RISER TUBES, AND MEANS INCLUDING EXTERNAL DOWNCOMERS FOR FLUID FLOWFROM SAID LOWER DRUM TO THE LOWER END OF THE REMAINING SEGMENTAL PORTIONOF THE CIRCUMFERENTIAL ROW OF TUBES IN SAID WALL, SAID LAST NAMED TUBESFORMING RISER TUBES EXTENDING UPWARDLY ALONG THE CORRESPONDING SEGMENTALPORTION OF THE WALLS OF SAID SETTING TO DISCHARGE INTO SAID UPPER DRUM.